Being on steroids shouldn't make you any more susceptible to catching a viral infection - steroids are anti-inflammatory medications, not immuno-suppressants. When I had shingles I was put on prednisone and an anti-viral, so I wouldn't worry on that score. As for your friend with Bell's Palsy, whatever the virus was that triggered the palsy (and it wasn't necessarily the one that causes shingles), it might not still be active and he wouldn't therefor be able to infect you. Here's a good link about Bell's Palsy though, including risk factors.

Lynn, my brother in law has had Bell's Palsy almost a year. He is much better than when first diagnose. He just happen to be in great contact with his mother in law and she was in the hospital with a severe case of Shingles. He was helping her up and down out of bed and gave her hugs at night. He had no idea he could contact this disease. I guess when there are chances of contacting anything like that we should try to guard ourselves however we can. The shingles shot is available to many as of 2011 with many insurances. It use to be by age for us to be covered now that isn't true.